mappedbytebuffer | 易学教程

Converting Bitmap to ByteBuffer (float) in Tensorflow-lite Android

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问题 In tensorflow-lite android demo code for image classification, the images are first converted to ByteBuffer format for better performance.This conversion from bitmap to floating point format and the subsequent conversion to byte buffer seems to be an expensive operation(loops, bitwise operators, float mem-copy etc).We were trying to implement the same logic with opencv to gain some speed advantage.The following code works without error; but due to some logical error in this conversion, the

MappedByteBuffer slow on initial run

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问题 long time reader, first time poster. I'm having a bit of trouble reading data quickly from a set of binary files. ByteBuffers and MappedBytBuffers offer the performance I require but they seem to require an initial run to warm up. I'm not sure if that makes sense so here's some code: int BUFFERSIZE = 864; int DATASIZE = 33663168; int pos = 0; // Open File channel to get data FileChannel channel = new RandomAccessFile(new File(myFile), "r").getChannel(); // Set MappedByteBuffer to read

MappedByteBuffer slow on initial run

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How do I avoid mapFailed() error when writing to large file on system with limited memory

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问题 I have just encountered an error in my opensrc library code that allocates a large buffer for making modifications to a large flac file, the error only occurs on an old PC machine with 3Gb of memory using Java 1.8.0_74 25.74-b02 32bit Originally I used to just allocate a buffer ByteBuffer audioData = ByteBuffer.allocateDirect((int)(fc.size() - fc.position())); But for some time I have it as MappedByteBuffer mappedFile = fc.map(MapMode.READ_WRITE, 0, totalTargetSize); My (mis)understanding was

How to properly close MappedByteBuffer?

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This is the code I'm running: import java.io.RandomAccessFile; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; public class Main { public static void main(String[] args) throws Exception { String filePath = "D:/temp/file"; RandomAccessFile file = new RandomAccessFile(filePath, "rw"); try { MappedByteBuffer buffer = file.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, 128); // Do something buffer.putInt(4); } finally { file.close(); System.out.println("File closed"); } System.out.println("Press any key..."); System.in.read(); System.out.println("Finished"); } }

How to properly close MappedByteBuffer?

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问题 This is the code I'm running: import java.io.RandomAccessFile; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; public class Main { public static void main(String[] args) throws Exception { String filePath = "D:/temp/file"; RandomAccessFile file = new RandomAccessFile(filePath, "rw"); try { MappedByteBuffer buffer = file.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, 128); // Do something buffer.putInt(4); } finally { file.close(); System.out.println("File closed")